In a Long Term Evolution (LTE) system, it is stipulated that when there is no uplink data required to be sent, physical uplink control channels are sent on fixed time-frequency resources. As shown in FIG. 1, one physical uplink control channel occupies one resource block in the frequency domain (one resource block occupies 12 sub-carriers) and lasts for two timeslots, namely one subframe (1 ms) in the time domain, and according to different cyclic prefixes used by the current subframe, the included symbolic numbers are different. In addition, the control channels perform frequency hopping on two timeslots so as to obtain diversity gain of the frequency domain. The physical uplink control channels of all User Equipments (UEs) in the cell are multiplexed through code division. Since the number of UEs which can be multiplexed on one resource block is limited, when the number of UEs required to send the physical uplink control channels simultaneously within the cell exceeds the number of users who can be multiplexed with one resource block, another resource block can be developed, that is, multiplexing of the physical uplink control channels of all the UEs in the cell is implemented by means of code division plus frequency division.
Currently, in the LTE system, the physical uplink control channels can support various uplink control signalings, including ACKnowledgement/Non-ACKnowledgement (ACK/NACK) information and Channel State Information (CSI) in which a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), a Rank Indicator (RI), a Scheduling Request (SR) and a combination of them are included, wherein the ACK/NACK information and SR are sent using a control channel format 1, and the CSI is sent using a control channel format 2. Specifically, the control channel format 1 is used for sending the SR, and a control channel format 1a/1b is used for sending ACK/NACK information of 1 bit/2 bits; the control channel format 2 is used for sending the CSI and sending the CSI and ACK/NACK information simultaneously under a frame structure with a spread cyclic prefix; and a control channel format 2a/2b is used for sending the CSI and ACK/NACK information of 1 bit/2 bits simultaneously under a frame structure with an normal cyclic prefix. For easy to understand, all kinds of the physical uplink control channels are firstly introduced in brief here.
As shown in FIG. 2, under the frame structure with an normal cyclic prefix, the ACK/NACK information goes through Binary Phase Shift Keying (BPSK)/Quadrature Phase Shift Keying (QPSK) modulation and forms a modulation symbol, the modulation symbol firstly performs a spectrum spread with a spreading factor of 12 in the frequency domain (a spread spectrum sequence is a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence with a length of 12), and goes through a time domain spreading of a Walsh sequence with a length of 4 in the time domain, and then is mapped to an information symbol corresponding to the control channel format 1a/1b as shown in FIG. 2, and finally forms a signal to be sent in one timeslot together with a reference signal. Therefore, within one resource block, the number of UEs which can multiplex to send the ACK/NACK simultaneously is decided by the number of shorter orthogonal sequences of time domain and the number of cyclic shifts of the CAZAC sequences permitted to be used in the same orthogonal code. When the cyclic prefix is the normal cyclic prefix, the number of available orthogonal sequences is 3, and when the cyclic prefix is the spread cyclic prefix, the number of available orthogonal sequences is 2, but the numbers of cyclic shifts of the CAZAC sequences permitted to be used in the same orthogonal sequence are different according to different application scenarios.
With regard to SR information, when there is an SR required to be sent, the SR information is fixedly modulated as d(0)=1, and then it is sent on the control channel format 1 by the same way as the ACK/NACK information.
As shown in FIG. 3, CSI information bits are coded to obtain 20 coding bits, and then go through the QPSK modulation to obtain 10 modulation symbols S0˜S9, each modulation symbol performs spectrum spread with the spreading factor of 12 in the frequency domain (the spread spectrum sequence is the CAZAC sequence with the length of 12), and then is mapped to an information symbol corresponding to the control channel format 2 as shown in FIG. 3, and finally forms a signal to be sent in one timeslot together with a reference signal. Therefore, within one resource block, the number of UEs which can multiplex to send the CQI simultaneously is decided by the number of cyclic shifts of the CAZAC sequences permitted to be used.
As shown in FIG. 4, when it is required to send the ACK/NACK and uplink channel Sounding Reference Signal (SRS) simultaneously on the same subframe and simultaneous transmission of the ACK/NACK and SRS is permitted by parameters configured by the higher layer, a physical uplink control channel format 1/1a/1b needs to use a truncated format, that is, the last data symbol of the subframe needs to be truncated, and the truncated data symbol is used for sending the SRS. Therefore, with regard to the truncated control channel format 1/1a/1b, a time domain spread sequence length of a data symbol of the second timeslot thereof will change from 4 to 3, and meanwhile, the used time domain spread sequence changes from a 4-order Walsh code to a 3-order Discrete Fourier Transformation (DFT) sequence.
In a general case, a UE sending the ACK/NACK and a UE sending the CSI use different resource blocks, but it is also supported that the ACK/NACK and CSI of different UEs are sent on the same resource block in the LTE currently, and it is stipulated that there is only one such resource block at most, and it is called as a hybrid resource block here, and when a parameter configured by the higher layer NCS(1)>0, it is indicated that the hybrid resource block exists.
In the LTE, the resource allocation of physical uplink control channels is as shown in FIG. 5, from the bandwidth edge to the bandwidth center, they are the control channel format 2/2a/2b area, the hybrid resource block (if configured) and control channel format 1/1a/1b area in sequence. Wherein, the physical uplink control channel resource of the control channel format 2/2a/2b area is represented with a channel index nPUCCH(2) and it is configured semi-statically by the higher layer signaling, and the physical uplink control channel resource of the control channel format 1/1a/1b area is represented with a channel index nPUCCH(1), and they can be configured semi-statically by the higher layer signaling and also can be indicated implicitly and dynamically through a downlink control channel.
In order to satisfy the requirements of International Telecommunication Union-Advanced (ITU-Advanced), a Long Term Evolution Advanced (LTE-A) system, as an advanced standard of the LTE, is required to support a wider system bandwidth (up to 100 MHz) and is required to be downward compatible with the existing standard of the LTE. Based on the existing LTE system, the bandwidth of the LTE system can be combined to obtain a wider bandwidth, this technology is called as a Carrier Aggregation (CA) technology, and the technology can improve spectrum efficiency of an International Mobile Telecommunications-Advanced (IMT-Advanced) system and relieve the shortage of spectrum resources, thereby optimizing the utilization of the spectrum resources.
When the LTE-A uses the carrier aggregation technology, and when the UE configures 4 downlink component carriers, the UE is required to feed back the ACK/NACKs of these 4 downlink component carriers. If the UE is required to feed back the ACK/NACK of each code word in the case of Multiple Input Multiple Output (MIMO), when the UE configures 4 downlink component carriers, the UE is required to feed back 8 ACK/NACKs. It can be seen from the above analysis that, 2-bit information can be carried at most when using the control channel format 1a/1b used by the ACK/NACK information. In Time Division Multiplexing (TDD) of the LTE, when the ACK/NACK feeds back ACK/NACK message by means of multiplexing, through the way of combining the channel selection and control channel format 1b, the ACK/NACK message which can be carried is enabled to support 4 bits at most, but with regard to more feedback bits, the current control channel formats of the LTE cannot support them. Therefore, it is extremely necessary to introduce new control channel formats. In the current LTE-A discussion, one conclusion is to introduce a format based on Discrete Fourier Transformation Spread-Orthogonal Frequency Division Multiplexing (DFT Spread-OFDM), which is used for the UEs which support more than 4 bits to perform the feedback of the ACK/NACK message. For an easy description, this new format based on the DFT-S-OFDM is called as a control channel format 3. At present, there is not a certain scheme with respect to a resource allocation method and a channelization method for the control channel format 3.